Abstract C122: Androgen receptor-mediated regulation of innate immunity in prostate cancer in Black men

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Abstract Black men are two times more likely to die from prostate cancer (PCa) than White men. We reported that innate immune cell infiltration varies between races, and others have reported differences in androgen receptor (AR) expression by race or ancestry. Herein, we evaluated AR status and immune cell infiltration in primary and metastatic PCa tissues obtained from Black and White men. RNA in situ hybridization (RISH) AR analysis was done on a tissue microarray (TMA) constructed from radical prostatectomy tissues from 120 Black men matched to 60 White men on age, grade and stage. RISH or immunohistochemistry (IHC) analysis of AR, NKX3.1, prostate specific antigen (PSA), mast cells (tryptase), neutrophils (CD66), and macrophages (CD206, CD68, CD80) was done on a TMA containing rapid autopsy tissues from metastatic sites (n=11) collected from Black (n=5) and White (n=16) men. Multiplexing IHC (mIHC) was used to assess AR, neutrophils (CD66ce), mast cells (tryptase), T-cells (CD4, CD8), and M2 macrophages (CD163) on radical prostatectomy whole-tissue sections obtained at Johns Hopkins Medicine, Baltimore, MD and biopsy tissues obtained from the University of Nairobi, Nairobi, Kenya. Tumor regions on TMAs were annotated by a pathologist and signal intensity per unit area measured using TMAJ and FrIDA software. HALO Image Analysis Platform (version 3.6.4134.137; Indica Labs) was used to analyze mIHC stained tissues. Statistical analysis and graphing were done using GraphPad Prism. There was increased AR mRNA expression in primary cancer tissues from Black men compared to White men (p<0.0001) after negative binomial regression with the adjustment of TMA set, age, grade and stage. There was a negative correlation between AR expression and CD66+ neutrophils in tumor and benign tissues from Black men (R = -0.318;p = 0.002) but this correlation was not significant among White men (R= -0.045; p = 0.765). Interestingly, we measured a positive correlation between AR mRNA expression and tryptase+ mast cells among White men (R= 0.320; p=0.016), but a trend toward a negative relationship among Black men (R= -0.252;p = 0.075) We also measured a positive correlation between AR and CD163+(R= 0.324; p<0.001), CD68+(R= 0.514;p<0.001), and CD80+(R= 0.386;p<0.001) macrophages in primary tumor tissues from all men. NKX3.1 and PSA protein were significantly increased in metastatic tissues from White compared to Black men. Conversely, CD68+ and CD80+ macrophages were increased in Black compared to White men. CD66+ neutrophils and CD206+ macrophages were increased in AR- compared to AR intact metastatic tissues. Immune cells appeared to be primarily void of AR expression in primary cancer tissues by mIHC, but there was a subset CD4+ and CD8+ T-cell clusters that express AR. Immune cell infiltration varies by the presence of AR in both primary and metastatic PCa tissues. We observed differences in AR mRNA and AR-related proteins between Black and White patients which may contribute to the differences observed in immune cell infiltration between the two races Citation Format: Kennedy Rains, Katie M. Farkouh, Taylor N. Godwin, Eric Erak, Aakash Parikh, Michael Considine, Elana Fertig, Jiayun Lu, Charles Waihenya, Valerie Odero-Marah, Karen S. Sfanos, Angelo M. De Marzo, Corinne E. Joshu, Janielle P. Maynard. Androgen receptor-mediated regulation of innate immunity in prostate cancer in Black men [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C122.